Java：从字符串中提取值？

Question

I'm new to Java and am trying to extract values from a date-related user input string and split it into a DD-MM-YYYY format.

I tried to use the code below:

String inputString = "s.param1"; 
String[] arraySplit_3 = inputString.split("-");
for (int i=0; i < arraySplit_3.length; i++){
    System.out.println(arraySplit_3[i]);
}

s.param1 gets the input of the user, I use a separate excel file for it.

if s.param1 = 15-05-2010

I wish to get this output:

DD: 15

MM: 05

YYYY: 2010

Is there a way to create a method like this?

Answer 1

Use java.time.LocalDate to parse this.

// dd: Day of Month
// MM: Month of year
// yyyy: year, four digits
DateTimeFormatter format = DateTimeFormatter.ofPattern("dd-MM-yyyy");
LocalDate date = LocalDate.parse(inputString);
System.out.printf("DD: %d%nMM: %d%nYYYY: %n", 
    date.getDayOfMonth(), date.getMonthValue(), date.getYear());

Answer 2

You are almost there, but maybe do not bother using a loop

String inputString = "15-05-2010"; 
String[] arraySplit_3 = inputString.split("-");
System.out.println("DD: " + arraySplit_3[0]);
System.out.println("MM: " + arraySplit_3[1]);
System.out.println("YYYY: " + arraySplit_3[2]);

But if you are wanting something more exotic look for SimpleDateFormat

Answer 3

Why you don't pars to date/calendar Object ?

String input = "15-05-2010";
SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy");
Date date = format.parse(input);
Calendar calendar = Calendar.getInstance() ;
calendar.setTime(date);
System.out.println(calendar.get(Calendar.YEAR));
System.out.println(calendar.get(Calendar.MONTH));
System.out.println(calendar.get(Calendar.DAY_OF_MONTH));

Answer 4

If your s.param1 is variable which gets date in String, so you shouldn't use it in quotes. Otherwise it will be String. And variable name could not be with dot . It could be sParam1 .
But when you set date instead of s.param1 your created method should work.

// input "15-05-2010"
String inputString = sparam1; 
String[] arraySplit_3 = inputString.split("-");
for (int i=0; i < arraySplit_3.length; i++){
    System.out.println(arraySplit_3[i]);
}

The output will be:
15
05
2010

If you want to add some chars before the numbers don't use for loop. Use it like this:

// ...
if (arraySplit_3 > 2) {
    System.out.println("DD: " + arraySplit_3[0]);
    System.out.println("MM: " + arraySplit_3[1]);
    System.out.println("YYYY: " + arraySplit_3[2]);
}

Then output will be:
DD: 15
MM: 05
YYYY: 2010

Answer 5

If you want to use a loop for that i would suggest You to create spearated method for splitting values here i have an example code

public class licz {
public static void main(String[] args) {

    List<String> list = new ArrayList<String>();
    list.add("15-05-2010");
    list.add("18-02-2015");
    extractValues(list);
}

private static void extractValues(List<String> list) {
    int change = 0;
    for (int i=0; i < list.size(); i++) {
        String[] split = list.get(i).split("-");
        for (String splitElement : split) {
            switch (change) {
                case 0:
                    System.out.println("DD: " + split[0]);
                    change++;
                    break;
                case 1:
                    System.out.println("MM: " + split[1]);
                    change++;
                    break;
                case 2:
                    System.out.println("YYYY: " + split[2]);
                    change=0;
                    break;
            }
        }
    }
}

}